President Obama’s jobs bill meets its first big test on Tuesday as the Senate moves toward a vote on whether to take up the legislation, the centerpiece of Obama’s efforts to revive the economy.

If that effort fails to achieve the necessary 60 votes, as many Republicans and some Democrats predict, Senate Democrats may try to break up the bill into more palatable pieces and press for votes on the individual parts. That is what Mr. Obama said was his preference in what sounded like almost an outright acknowledgement that Congress would reject his jobs proposal. “If they don’t pass the whole package, we’re going to break it up into different parts,” Mr. Obama said Tuesday during a jobs-related meeting in Pittsburgh, echoing White House officials who have said that they would seek to push those parts of the bill with the most chance of passage.

Alternatively, if the bill does not pass, Senate Democrats might join a handful of Republicans in searching for areas where the two parties might agree — a formidable challenge in a chamber where comity seems to worsen by the week.

In speeches around the country, Mr. Obama has assailed Republicans for blocking his jobs bill. While Mr. Obama can count on the support of a majority of Senate Democrats, a few moderate-to-conservative Democrats, including some who have to face re-election next year in states the president lost in 2008, have said they were leaning against the bill or refused to say how they would vote.